[DevTools] Add breadcrumbs to Suspense tab

packages/react-devtools-shared/src/devtools/views/SuspenseTab/SuspenseBreadcrumbs.css

@@ -0,0 +1,33 @@
+.SuspenseBreadcrumbsList {
+  margin: 0;
+  padding: 0;
+  list-style: none;
+  display: flex;
+  flex-direction: row;
+  flex-wrap: nowrap;
+}
+
+.SuspenseBreadcrumbsListItem {
+  display: inline;
+}
+
+.SuspenseBreadcrumbsListItem[aria-current="true"] .SuspenseBreadcrumbsButton {
+  color: var(--color-button-active);
+}
+
+.SuspenseBreadcrumbsButton {
+  background: var(--color-button-background);
+  border: none;
+  border-radius: 0.25rem;
+  padding: 0.25rem;
+  white-space: nowrap;
+}
+
+.SuspenseBreadcrumbsButton:hover {
+  background-color: var(--color-button-background-hover);
+  color: var(--color-button-hover);
+}
+
+.SuspenseBreadcrumbsButton:focus-visible {
+  background: var(--color-button-background-focus);
+}

packages/react-devtools-shared/src/devtools/views/SuspenseTab/SuspenseBreadcrumbs.js

@@ -0,0 +1,79 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow
+ */
+
+import type {SuspenseNode} from 'react-devtools-shared/src/frontend/types';
+
+import * as React from 'react';
+import {useContext} from 'react';
+import {
+  TreeDispatcherContext,
+  TreeStateContext,
+} from '../Components/TreeContext';
+import {StoreContext} from '../context';
+import {useHighlightHostInstance} from '../hooks';
+import styles from './SuspenseBreadcrumbs.css';
+import typeof {SyntheticMouseEvent} from 'react-dom-bindings/src/events/SyntheticEvent';
+
+export default function SuspenseBreadcrumbs(): React$Node {
+  const store = useContext(StoreContext);
+  const dispatch = useContext(TreeDispatcherContext);
+  const {inspectedElementID} = useContext(TreeStateContext);
+
+  const {highlightHostInstance, clearHighlightHostInstance} =
+    useHighlightHostInstance();
+
+  // TODO: Use the nearest Suspense boundary
+  const inspectedSuspenseID = inspectedElementID;
+  if (inspectedSuspenseID === null) {
+    return null;
+  }
+
+  const suspense = store.getSuspenseByID(inspectedSuspenseID);
+  if (suspense === null) {
+    return null;
+  }
+
+  const lineage: SuspenseNode[] = [];
+  let next: null | SuspenseNode = suspense;
+  while (next !== null) {
+    if (next.parentID === 0) {
+      next = null;
+    } else {
+      lineage.unshift(next);
+      next = store.getSuspenseByID(next.parentID);
+    }
+  }
+
+  function handleClick(node: SuspenseNode, event: SyntheticMouseEvent) {
+    event.preventDefault();
+    dispatch({type: 'SELECT_ELEMENT_BY_ID', payload: node.id});
+  }
+
+  return (
+    <ol className={styles.SuspenseBreadcrumbsList}>
+      {lineage.map((node, index) => {
+        return (
+          <li
+            key={node.id}
+            className={styles.SuspenseBreadcrumbsListItem}
+            aria-current={index === lineage.length - 1}
+            onPointerEnter={highlightHostInstance.bind(null, node.id)}
+            onPointerLeave={clearHighlightHostInstance}>
+            <button
+              className={styles.SuspenseBreadcrumbsButton}
+              onClick={handleClick.bind(null, node)}
+              type="button">
+              {node.name}
+            </button>
+          </li>
+        );
+      })}
+    </ol>
+  );
+}

packages/react-devtools-shared/src/devtools/views/SuspenseTab/SuspenseTab.css

@@ -108,14 +108,22 @@
   overflow: auto;
 }
 
-.TimelineWrapper {
+.SuspenseTreeViewHeader {
   padding: 0.25rem;
-  display: flex;
-  flex-direction: row;
+  display: grid;
+  grid-template-columns: auto 1fr auto;
   align-items: flex-start;
 }
 
-.Timeline {
-  flex-grow: 1;
-  align-self: anchor-center;
+.SuspenseTreeViewHeaderMain {
+  display: grid;
+  grid-template-rows: auto auto;
+}
+
+.SuspenseBreadcrumbs {
+  /**
+   * TODO: Switch to single item view on overflow like OwnerStack does.
+   * OwnerStack has more constraints that make it easier so it won't be a 1:1 port.
+   */
+  overflow-x: auto;
 }

packages/react-devtools-shared/src/devtools/views/SuspenseTab/SuspenseTab.js

@@ -19,6 +19,7 @@ import InspectedElementErrorBoundary from '../Components/InspectedElementErrorBo
 import InspectedElement from '../Components/InspectedElement';
 import portaledContent from '../portaledContent';
 import styles from './SuspenseTab.css';
+import SuspenseBreadcrumbs from './SuspenseBreadcrumbs';
 import SuspenseRects from './SuspenseRects';
 import SuspenseTimeline from './SuspenseTimeline';
 import SuspenseTreeList from './SuspenseTreeList';
@@ -304,10 +305,15 @@ function SuspenseTab(_: {}) {
           />
         </div>
         <div className={styles.TreeView}>
-          <div className={styles.TimelineWrapper}>
+          <div className={styles.SuspenseTreeViewHeader}>
             <ToggleTreeList dispatch={dispatch} state={state} />
-            <div className={styles.Timeline}>
-              <SuspenseTimeline />
+            <div className={styles.SuspenseTreeViewHeaderMain}>
+              <div className={styles.SuspenseTimeline}>
+                <SuspenseTimeline />
+              </div>
+              <div className={styles.SuspenseBreadcrumbs}>
+                <SuspenseBreadcrumbs />
+              </div>
             </div>
             <ToggleInspectedElement
               dispatch={dispatch}

packages/react-devtools-shared/src/devtools/views/SuspenseTab/SuspenseTimeline.css

@@ -2,6 +2,7 @@
   width: 100%;
   display: flex;
   flex-direction: row;
+  padding: 0 0.25rem;
 }
 
 .SuspenseTimelineInput {